The Fraternal Gambit
by samwise of tardis
Summary: Sherlock and Mycroft Holmes; a rivalry with far more history than their recent battles with Moriarty. Two brilliant minds grudgingly working together for the good of England (and their own entertainment.) But beneath the banter, these brothers are locked in a battle for control that will bring into play all their friends and resources, and even their enemies... 12 chapters in all.
1. All Systems Go

**Chapter 1: All Systems Go**

_Sherlock:_

Sherlock Holmes stared out the window of the jet plane that was to carry him to his exile, and wondered how long it would be before his brother called him back _this _time. Sherlock was perfectly aware that he was not going to have to endure the permanent exile and probable death of his official sentence, and he was looking forward to letting his genius loose abroad for a while before Mycroft found a use for him and had him hauled back again.

Mrs. Hudson, had she been aware of the way the elder Holmes boy moved his brother around at will, would have called it shameful and unfeeling. She was half right, Sherlock reflected; Mycroft's actions were in no way influenced by the messy human emotions that Mycroft so thoroughly disapproved of. Mycroft's hatred of sentiment was second only to his hatred of chaos. And unlike Sherlock, Mycroft didn't even seem to experience boredom. Well, not anymore. Unbidden, the image of twelve-year-old Mycroft, already wearing a suit and tie everywhere, fixing his five-year-old brother with a look of annoyance and saying "For heaven's sake Sherlock, do stop being so willfully boring all the time." He would usually follow this by forcing sherlock to solve increasingly difficult puzzles, only to waltz in, smash them up, and do it himself in half the time.

He stopped doing this after Sherlock got frustrated enough to set fire to the cat.

No, if Sherlock was any judge, the only emotion Mycroft Holmes allowed himself was loyalty. Loyalty drove him to endure the torture of a Drury Lane production when their parents were in town. Loyalty drove him to officially hold only a low-paying position in the government he technically ran, and to choose the country of his birth as his domain instead of the more powerful countries of Europe.

Oh, and one other emotion, too...

The planes engines fired up, and Sherlock's eyes moved to look one last time at John Watson, his...his friend. Even after all this time, the word felt foreign on his tongue. _My best friends, John and Mary Watson,_ he thought. _I really don't deserve them._

Sherlock hoped that John had correctly interpreted the carefully coded message he had given him moments before.

"William Sherlock Scott Holmes. That's the whole of it."

"The Game is never over. There are just some new players now."

"He was a rubbish big brother."

And, of course,

"Sherlock is actually a girl's name."

John had seemed pretty clueless, but then, that was what John generally pretended to be. But was it real this time…?

Then John caught Sherlock's eye, gave a stiff nod and a salute, and Sherlock knew he had gotten the message. He could trust the Watsons to carry out the Plan.

As the jet rose above the clouds, Sherlock allowed himself a smile. _The Plan advances._

"Your move, brother mine," he murmured. "Your move."


	2. Preparations for War

**Chapter 2: Preparations for War**

_John:_

John Hamish Watson stood by the runway and watched his best friend in all the world boarding the plane that was to take him away, "forever." Again.

Of course, John knew now, as he knew then, that Sherlock would be back eventually. But this time, he promised himself, he would not allow himself to doubt it.

…

When your best friend's big brother is Big Brother himself, it is very difficult to plan behind his back. Even setting up a code was dangerous, as Mycroft would be sure to overhear the key. Even with the variety of systems the two men had devised, the process of coded communication was infuriatingly slow: a military term here, a seemingly accidental emphasis of the wrong syllable there, a bit of Morse code blinked or scrawled on a napkin.

Then there was the night when Sherlock, using a carefully stacked game of Cluedo, informed him that he, Sherlock, was plotting suicide. John had been so angry he'd stuck a knife in the board before Sherlock could say, "Oh, come on, John, it isn't real, " and, with his back to where they were pretty sure the camera was, winked.

John was still halfway through his retort before he realized that this, too, was part of the code. "Setting aside that it is not possible for the victim to be the murderer," John said, "why on earth would he want to?"

"Impossible is just a word, John," Sherlock said mildly, "and people will kill themselves for any number of reasons. I know of a man who jumped out the window because someone brought a pineapple to his party."

This was not the nonsense it appeared to be. John knew that in certain areas, 'pineapple' was a slang term for a grenade.

So, he'd reasoned, Sherlock wanted to fake his death to somehow save a group of people. But further than that, he'd not been able to get anything out of his friend during the months of planning and preparation. When Sherlock suggested they play Cluedo again, John knew it was time to put their Plan into action.

Now it was happening again. But this time, Dr. John H. Watson was not in the dark. He knew perfectly well why Sherlock was going.

John looked down at the slip of paper Sherlock had slipped into his palm when they shook hands. It read, "up2u. Advance the game. U.M.Q.R.A."

Dr. Watson smiled.

This time, it was up to John to get him back.


	3. Counter-Intelligence

**Chapter 3: Counter-Intelligence**

_Mycroft:_

[Earlier that day]

Mycroft Holmes, unofficial head of security and justice for the United Kingdom of Great Britain, leaned back in his desk chair idly sipping a cup of tea, and considering carefully recent events.

It really was rather a nuisance that Sherlock had gone and shot that fool Magnussen. Why hadn't he stuck to the plan? But then, Mycroft had never understood his younger brother. Even as children, Sherlock had always taken offence to Mycroft's attempts to teach him, to challenge and occupy him; and yet the boy was so constantly bored that he was always getting into trouble.

Then there was the day Sherlock, age 17, had come home with a skull and refused to tell anyone how he had obtained it. That was the day Mycroft really began to worry about his brother's future. The boy simply got involved too much; he couldn't help himself. Mycroft had secretly hoped that his brother might learn to be more aloof when his pet dog, Redbeard, was run over by an HGV, but the self-enforced isolation which ensued did little to stem the tide of young Sherlock's delinquency.

Things had gotten better, for a while, once John Watson turned up. John's soldier instincts allowed him to keep up with Sherlock, even if his mental acuity was frankly deplorable, even compared to Sherlock's. At the same time, he had a keen sense of morality, and the force of will to keep Sherlock somewhat in check.

But somewhere along the line, it had all gone wrong. Sherlock had become too attached. He and Mycroft had argued about it many times, late into the night. But whatever Sherlock said, it was clear to Mycroft that John Watson was clouding Sherlock's judgement, and botched jobs like this were the result.

It had been a simple plan: Sherlock was to [carefully] drug the family, then steal his brother's laptop: one fastidiously prepped with GPS and several incriminating files, some with evidence of tampering masterfully applied beforehand. Mycroft would follow the signal to Magnussen's hideout, arrest him and Sherlock both. After severe questioning, Sherlock would be pardoned and Magnussen released in exchange for the incriminating evidence on Mary Watson and a document signed by Magnussen to ensure the man could not attempt to blackmail her ever again. Yet for some unfathomable reason, Sherlock had instead shot the man, and now it had all gone pear-shaped.

Mycroft had himself created and planted the files on MI6 Agent 43552, alias criminal assassin A. G. R. A, alias Mary Watson, nee Morstan. About a month ago, his counter-intel discovered that Charles Augustus Magnussen had been tipped off by an anonymous informant that Mary Watson was not what she seemed. Mycroft had acted quickly to erase all evidence of his connection with the agent, planting a thorough and believable dark past in its place. As per instructions, Agent 43552 had allowed her cover to be "blown" by Sherlock holmes, leading to his and John's acceptance of her as A. G. R. A, and to their willingness to help Mycroft pull in Magnussen and ensure the safety of his operative.

With Magnussen dead, however, there was no way to discover the informant's identity. Someone out there knew something about 43552. Mycroft Holmes had, for the moment, no way to ensure the safety of his agent.

He leaned forward and pressed a button on his intercom. "For the safety of the agency, I'm downgrading Agent 43552 to a sleeper cell. She is to maintain her cover until further notice." He allowed himself a brief smile. "Offer Mrs. Watson my congratulations on her marriage, and on a job well done."


	4. Subversion

**Chapter 4: Subversion**

_John:_

Dr. John Watson was a soldier. He'd been in service in Afghanistan. True, he'd been working largely in the medical tent, but he'd had more than a few days pinned down under fire. There had been ambushes, raids, air strikes, once even a clash with a defecting squadron.

He'd also seen a fair few spies come and go. Some were caught. Others were noticed quietly joining the enemy ranks during an ambush. Others were double agents, not really spying on them at all, but _for_ them. Dr. Watson had known many of them and interviewed them all, as part of the routine health inspection. He'd picked up how to tell when someone was lying about who they were. In fact, the battle that had broken out on his last day of active duty could have been totally avoided if his C.O. would have listened to his doubts about Corporal Roberts. He felt a twinge in his shoulder at the memory of that battle: six dead, three wounded, including the Senior Medical Captain, John H. Watson.

As such, John spotted instantly that Mary Morstan was not all she seemed. He thought originally that she might be looking for Sherlock. His friend _had _suggested that Moriarty might send agents to confirm Sherlock was not alive and in secret correspondence with John, and so John had played along, opening up to her about his feelings about Sherlock's "Death."

He was surprised and curious to discover she had no apparent interest in Sherlock, and was very supportive of John as he dealt with his emotions.

It had been 11 months with not a word from Sherlock. John was beginning to worry that he really _had_ died, or had been killed whilst doing...whatever it was he was doing abroad. John was able, through clever rewording, to talk about some of this to Mary, and she was a great help to him. By the time John had figured out fairly well who she was, it no longer mattered. John's intuition, along with some techniques he'd picked up from their own espionage unit back with the Fifth Northumberland Fusiliers, told him that whatever lie she was living, her affection for him was as real as his for her.

He would have to get Sherlock to help him sort it out, if he ever decided to come back.


	5. Stalemate

**Chapter 5: Stalemate**

_Sherlock:_

It had been a year since Sherlock Holmes had faked his death. One year since he had apparently tumbled to an untimely demise. What did he have to show for it? Well, they hadn't caught on yet. He'd investigated three hundred twenty-six false leads, sixty-three traps and ambushes, seventy-two glaringly obvious red herrings, and, in disguise, one hundred fifty-three side cases. He couldn't help it. He was always sure to do so from behind the scenes, though.

_I must act as my adversary,_ he thought. _The hand of the player must never be seen._

He'd also evaded ninety-six of his elder brother's employees. This wasn't strictly necessary, but Sherlock enjoyed keeping Mycroft in the dark. Let Mycroft worry about him. Let it build up as no-one sees him for a while. Then, let some desperate agent catch up and, over coffee, feed them a string of entertaining lies.

But there had been nothing, none of these, for three months now. The impasse was getting frustrating.

Sherlock looked at his phone and resisted the urge to text John. _I have no idea where he is, or who is watching. _But, oh, it did hurt, having to keep John in the dark, too.

That was, however, one of the main reasons Sherlock was here. After that near-disaster with The Woman, Mycroft and Sherlock had argued nonstop for months over Sherlock's "dangerous tendency to attachment." Sherlock had insisted that his friendships were not dangerous, that he did not allow them to affect his judgement (though this was probably a lie). He had let slip; The Woman had taken advantage of the Holmes weakness: pride. For Sherlock, this was a need to be appreciated, to show off. And he had, just once, been a little too comfortable and done so with someone who, though enamoured of him, had been good enough to keep that from affecting _her_. Oh, yes, she was good, The Woman. She was so good, she had been able to love him and still be his enemy. Much as he had her. In a bistro in France, Sherlock raised his mug in a silent toast to her.

Mycroft had been sure it was attachment and not pride that caused the debacle. Possibly because of his own pride, he would not give credence to his younger brother's argument. [Mycroft did not need to show off because he knew he was far too good for anyone to keep up. He showed off by _not_ revealing how good he was.] Even when Sherlock deliberately and repeatedly used John, Molly, Greg (whose name he would never admit to knowing), Mrs. Hudson, and the others as test subjects for a drug without their knowledge; despite the heartless comments he was perfectly comfortable making, and the rather cruel, if amusing "experiment" he'd pulled at Baskerville, Mycroft Holmes continued to show disdain. Well, more disdain than he normally did, anyway.

It was when Mycroft began, very subtly, to threaten these people, that Sherlock knew drastic action was called for. And so, he'd begun carefully setting himself up for Moriarty to pick him off.

A few years out of the country fighting crime without telling his associates should prove his resolve, even to Mycroft.

He hadn't really left them in the dark, of course. John knew he was alive, as did Molly, who Mycroft had actually dared call "an insignificant nothing." She would probably have killed herself otherwise, fragile bundle of emotions that she was, and Sherlock would never have forgiven himself. Dear, sweet Molly; so entertaining to tease, yet possessing the courage and insight to stand by him when he needed her most. In defiance of Big Brother, she was brought in on the plan. The others could know it, too, if they only paid attention to the signs.

There was another reason Sherlock was out here. He had realized Moriarty's secret not long after their second meeting, and was out to prove it. Sadly, he was being blocked at every turn, bringing him back to this little bistro, his base for the past week.

A man walked in. First glance told Sherlock this was an agent of MI6, and a junior one at that; his inexperience showed in his failed attempt to mask his anxiety. Sherlock gave him the slip easily, pulling out his phone and sending his brother a short text:

_A jr agent? tut tut. dont let ur attachment cloud ur judgement, brother dear. -SH_

The text he received in return sent a shiver down his spine as he realized: _that is no junior MI6 agent._

He watched for a few minutes until he saw the agent scurry out of the restaurant, looking all around very conspicuously. He smiled. _The stalemate is ended. The game is on!_


	6. Regent

**Chapter 6: Regent**

[one week before the events of "The Great Game."]

_?:_

The man sat in his office-well, _an _office, anyway- his feet up on the desk as he used his tablet to read through the day's Tributes.

Tributes were one of the man's favourite parts of his job. He'd worked hard to become a name both feared and respected in the underworld: the Napoleon of Crime, they called him.

He adjusted his tie and grinned to himself. They had no idea. He had killed, extorted, manipulated, and blackmailed his way to the top. _And this time, there will be no Waterloo._

Having established himself as the the most fearsome lawbreaker in England, the man had then gradually built up his criminal empire. By now, every crook in Great Britain paid Tribute to him.

Amongst thieves, tribute meant money, yes, but also a report of their activities, advance notice of big heists, even tabs on local small-time delinquents. Everyone told the man what laws they planned to break, and when; and they waited on his approval, too. In return, the man prevented two thieves picking the same target on the same night, which was always messy and usually involved the coppers. He found the less-skilled miscreants and hired them to run interference for those with loftier targets. And he could be trusted to know when a certain job was a bad idea. Those who went against the man's advice always ended up chained to a table opposite Lestrade, one of the Holmes brothers, or, if all else failed to go wrong, opposite the man himself. That was one place a crook never ended up twice.

Ah, yes. Sherlock Holmes. Now, _there _was a proper adversary. The man had originally thought Sherlock, well, a bit slow; but he'd been gradually getting closer and closer to discovering the truth. And so, the man had had to get..._creative._

The man leaned back in his chair and listened to the muffled sobbing of Mrs. Brook, mother of Richard Brook, coming from the closet as she tried to scream through her tape gag.

He smiled. It was good to be king.


	7. Deep Cover

**Chapter 7: Deep Cover**

_Mary:_

Sherlock embraced Mary Watson first as he prepared to board the private jet. "Take care of him," he said. It meant, _I trust you to take my place. _

"Don't worry," she replied. "I'll keep him in trouble."

It hadn't been long after Sherlock's return that Mary had revealed her identity to Sherlock and requested his help. She was an MI6 agent keeping John alive in Sherlock's absence; Sherlock's return would surely be followed by reassignment as soon as would be inconspicuous. But although Mary had been assigned to John Watson, over time she had genuinely fallen in love with him. She had begged Sherlock to find a way to let her stay, without getting into trouble with Mycroft Holmes, who, by all accounts, did not tolerate emotions and could do very nasty things to those who crossed him. Sherlock had accepted the case instantly, as much for the chance to play his elder brother as to help his friend, Mary suspected.

She was puzzled, then, that he seemed to be doing very little, and after the wedding he vanished altogether. A fortnight afterwards, Mycroft called her in for a briefing. Cursing Sherlock's inaction, she had made her way to the random building chosen for the rendez-vous while John was at work.

Mycroft himself had shown up, looking unusually agitated. He informed her that a journalist of some considerable power, and who had a history of blackmail, was caught investigating rumours about the hidden identity of Mary Watson. Although she had no idea why, Mary instantly guessed that Sherlock was behind it.

"What do you intend to do, sir?" she'd asked, doing her best to keep the nervousness out of her voice.

"I'm going to allow him to find information about you, agent 43552." Mycroft had replied.

Fear gripped Mary's heart. Was MI6 about to disown her?

"Though it will not, of course, be the truth of your service here at MI6." Mycroft continued. "you are to take on the role of an assassin, who has had a rather grisly past and is now hiding from it."

Her boss paused and allowed himself a brief, humorless smile. "Once my brother figures out who you are, or rather, who you seem to be, I'm quite sure he will be only too willing to show off his frankly average intelligence and loose approach to the law to get Mr. Magnussen out of the picture. We will, of course, be uninvolved." Mycroft slid a USB across the table to her. "This contains all you need to know about your cover. You are dismissed."

"Sir," Mary saluted. Then, unable to stop herself, she added, "What will happen once Magnussen is removed?"

Her boss gave her a reproving look. "That is none of your concern, agent 43552. You are dismissed."

On her way down the stairs, she received the text, from a withheld number:

_Queenside castle is a useful tactic for protecting your king and queen from attack. Next, focus on removing the rook._

There was no signature. None was needed.


	8. Supplements

**Interlude: Supplements**

_Mrs. Hudson:_

Mrs. Hudson would be the first to admit she wasn't necessarily the quickest horse from the gate, but no matter what the man said, she doubted that Her Boys would send in a handyman to fix things _in her own flat_ without letting her know about it first. Sweet John was so proper about everything, he'd've told her so she wouldn't worry about strange men in the house; Sherlock wouldn't bother hiring anyone in the first place. Put that with all the odd things Her Boys had been doing lately, and she thought it very odd indeed.

So, in the interest of being hospitable, Mrs. Hudson invited the burly handyman in, and then went about brewing tea. _Special_ tea, she thought, with a private grin at the pun.

She brought the man a cuppa just as he began unpacking his toolkit, and she masterfully restrained a shudder at the unmistakable sight of a disassembled sniper rifle. Her dear Sherlock had gone through a phase, disassembling dozens of firearms and leaving the pieces all over the flat for John to sit on and shout at him for, but she _remembered_ the sniper rifle because the stock of one had somehow ended up in her jar of soothers, and Sherlock had shouted at her for "disturbing an experiment"; the nerve!

After leaving the tea, Mrs. Hudson bustled off to dust the clutter-strewn living room, carefully watching the large man in a reflective beaker as he expertly snapped the weapon's pieces together… and then drained the cup of tea.

_Special_ tea.

The man blinked once, twice, then keeled over sideways, letting out a loud snore. Mrs. Hudson smiled brightly and went about her dusting, quite glad that John had finally badgered Sherlock into labeling his chemicals. She hadn't even needed to sacrifice any of her precious soothers… this time.


End file.
